Albert Daydreams (2025)

1. Space and Time in Classical Mechanics

I stand at the window of a railway carriage
I drop a stone on the embankment
I see it descend in a straight line
A pedestrian observes the misdeed from the footpath
A pedestrian notices that the stone falls to earth in a parabolic curve

2. The Equality of Inertial and Gravitational Mass as an Argument for the General Postulate of Relativity

In empty space
So far removed from stars
Imagine a spacious chest
A spacious chest so far removed from stars
With an observer inside

Gravitation does not exist for the observer inside
He fastens himself with strings to the floor
Otherwise, he will rise
Slowly toward the ceiling of the room

 

Text by Albert Einstein (Translated by Robert W. Lawson), from Relativity: The Special and General Theory (originally published in 1916, translation published in 1920)